For complementary upgrades, this makes no difference. I do this all the time where I buy F and waitlist a co-worker who bought Y. The co-worker always inherits my status at the gate. I do always have to ask the agent at the airport to relink them; I don't think this carries over from an advance waitlist request.

I don't know if there's a difference with SWUs, though, since those can be used for anyone regardless of whether you're also on the flight with them.